Flat heat pipe with composite capillary structure

ABSTRACT

A flat heat pipe with a composite capillary structure has a flat pipe with a flat and enclosed hollow pipe body including a top wall, a bottom wall, two lateral walls and a chamber. The flat pipe has an evaporation section and a condensation section. The elongated mesh grid is located onto either of the top and bottom walls in the chamber. The elongated mesh grid is extended from the evaporation section to the condensation section. The long porous sintered structure is located adjacent at least one lateral wall in the chamber. The long porous sintered structure is extended from the evaporation section to the condensation section. The porous sintered structure and the elongated mesh grid are prefabricated into a composite capillary structure. The flat heat pipe presents excellent diversion effect and stable positioning with its better vapor diversion space and simple manufacturing process.

CROSS-REFERENCE TO RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a flat heat pipe, and moreparticularly to an innovative one which is configured with a compositecapillary structure and fabricated by mould pressing.

2. Description of Related Art Including Information Disclosed Under 37CFR 1.97 and 37 CFR 1.98

The heat pipe is structurally configured with a capillary structure toenhance condensate return flow effectively.

A single capillary structure is employed by the conventional heat pipeto facilitate the condensate return flow, while a composite capillarystructure has been developed by the industrial operators to improve thediversion effect.

Despite that said composite capillary structure can realize bettercondensate diversion effect, a larger problem is encountered for itsmanufacturing process, especially when it is applied to flat heat pipe.This is because the flat heat pipe is generally made of round pipes bymeans of mould pressing, the capillary structure in the pipe, whether inthe form of mesh structure or sintered structure, is vulnerable todeformation, deflection and loosening during the flattening orevacuation sealing process. This results in serious problems such as:relatively higher defects and difficulty in quality control of finishedproducts. But said composite capillary structure is involved with themating accuracy and robustness of two capillary structures, so it isunderstood that the design problems become more complex and difficultwith possible higher defects in the manufacturing and poorer industrialbenefits.

Moreover, the thickness and space of the flat heat pipe is much lessthan that of the round pipe, so the vapor diversion space is reducedconsiderably. With the introduction of a composite capillary structure,the vapor diversion space will be further lessened for the given volumeand thickness in the flat heat pipe, thus affecting its heat conductioneffect.

Thus, to overcome the aforementioned problems of the prior art, it wouldbe an advancement if the art to provide an improved structure that cansignificantly improve the efficacy.

Therefore, the inventor has provided the present invention ofpracticability after deliberate experimentation and evaluation based onyears of experience in the production, development and design of relatedproducts.

BRIEF SUMMARY OF THE INVENTION

For the condensate diversion effect: with the structural configurationof the composite capillary structure wherein the elongated mesh grid ismated with the long porous sintered structure, the combined diversionstructure could help realize satisfactory diversion effect.

For the positioning of the composite capillary structure: the elongatedmesh grid provides an expanded positioning base for the long poroussintered structure, so that the composite capillary structure can bepositioned securely. The porous sintered structure and elongated meshgrid are combined and secured to form a composite capillary structure,which is placed inside the chamber of the flat pipe, so that thecomposite capillary structure can be assembled to the flat pipe easily,and achieve high stability and quality.

For the vapor diversion space: given the fact that the elongated meshgrid is thin-profiled and the long porous sintered structure is locatedadjacent to the flat pipe's lateral wall, the present invention canprovide maximum vapor diversion space for optimized heat conductanceperformance.

For the manufacturing process: the composite capillary structure of thepresent invention (composed of elongated mesh grid and a long poroussintered structure) is mated with the flat heat pipe in such a mannerthat the heat pipe is pre-pressed preliminarily and the elongated meshgrid is bent. When the composite capillary structure is placed, the heatpipe is pressed in place. With this configuration, it is possible toprovide a simple and stable manufacturing process for mating the flatheat pipe with the composite capillary structure.

Although the invention has been explained in relation to its preferredembodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the invention as hereinafter claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows an upper perspective view of the preferred embodiment ofthe flat heat pipe of the present invention.

FIG. 2 shows a partially exploded perspective view of the preferredembodiment of the present invention.

FIG. 3 shows a sectional view of the preferred embodiment of the presentinvention.

FIG. 4 shows another sectional view of the preferred embodiment of thepresent invention (sectional state of flat heat pipe).

FIG. 5 shows a sectional view of another preferred embodiment of thelong porous sintered structure of the present invention.

FIG. 6 shows another sectional view of the preferred embodiment of thelong porous sintered structure of the present invention (sectional stateof flat heat pipe).

FIG. 7 shows a schematic view of the present invention wherein theelongated mesh grid is provided with a local hollowed portion.

FIG. 8 shows a schematic view of the present invention wherein theelongated mesh grid is provided with a notch.

FIG. 9 shows sectional view of another preferred embodiment of the longporous sintered structure of the present invention.

FIG. 10 shows a perspective view of the preferred embodiment in FIG. 9.

FIG. 11 shows a schematic view of the present invention wherein the longporous sintered structure is provided with a depressed portion.

FIG. 12 shows a schematic view of the present invention wherein agrooved capillary structure is formed onto the inner wall of the flatpipe.

FIG. 13 shows a schematic view of the molding process of the presentinvention.

FIG. 14 shows a schematic view of the other molding process of thepresent invention.

FIG. 15 shows a schematic view of the present invention wherein theembryo flat pipe is pre-pressed and converted from the round pipe isarranged at a local section.

FIG. 16 shows another schematic view of the long porous sinteredstructure of the present invention.

FIG. 17 shows another schematic view of the elongated mesh grid of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-4 depict preferred embodiments of a flat heat pipe of thepresent invention with a composite capillary structure, which, however,are provided for only explanatory objective for patent claims.

Said flat heat pipe A comprises a flat pipe 10, made of metal into aflat and enclosed hollow pipe body, having a top wall 11, a bottom wall12, two lateral walls 13, 14 and a chamber 15. The flat pipe 10 has anevaporation section 16 and a condensation section 17, and both ends ofthe flat pipe 10 are enclosed (shown by C1, C2 in FIG. 1). Moreover, thechamber 15 is at an evacuation state. Alternatively, the chamber 15 ofthe flat pipe 10 is filled with working fluid.

At least one elongated mesh grid 20, made of metal, is located ontoeither of the top and bottom walls 11, 12 in the chamber 15 of the flatpipe 10. The elongated mesh grid 20 is extended from the evaporationsection 16 to the condensation section 17 of the flat pipe 10.

At least one long porous sintered structure 30, made of metal, islocated onto either position in the chamber 15 of the flat pipe 10 (thelong porous sintered structure 30 of the preferred embodiment is dividedinto two parts adjacent to two lateral walls 13, 14). The long poroussintered structure 30 is extended from the evaporation section 16 to thecondensation section 17 of the flat pipe 10.

Moreover, the porous sintered structure 30 and the elongated mesh grid20 are prefabricated securely into a composite capillary structure B,and the composite capillary structure B is placed between the top andbottom walls 11, 12 of the chamber 15 of the flat pipe 10.

Referring to FIG. 7, a local hollowed portion 21 is formed at thecentral section of the elongated mesh grid 20 between the evaporationsection 16 and condensation section 17 of the flat pipe 10. Moreover, acoupling surface of sintered structure 22 is reserved at the centralsection of the elongated mesh grid 20 for coupling the long poroussintered structure 30. In this preferred embodiment, the elongated meshgrid 20 can be further shrunk to provide a larger vapor diversion spacein response to the space-saving flat heat pipe, provided that the matingstate of the long porous sintered structure 30 is not affected.

Referring to FIG. 8, a single or a plurality of spacing notches 23(V-shaped or straight pattern) is arranged at local section of theelongated mesh grid 20, in response to the bending state of theelongated mesh grid 20. When the elongated mesh grid 20 is bent in tunewith the flat heat pipe, the bending portion permits one to prevent thecorrugation with the configuration of said notch 23. The mesh structurewill generate a corrugated surface at the bending portion without thedesign of notch.

Referring also to FIGS. 9 and 10, the long porous sintered structure 30is located within the chamber 15 of the flat pipe 10 at a spacing withthe lateral walls 13, 14. With this configuration, a vapor channel isformed between the long porous sintered structure 30 and lateral walls13, 14 to improve the diversion effect. Also, the cross section of thelong porous sintered structure 30 of the preferred embodiment is of arectangular shape.

Referring to FIG. 11, at least one depressed portion 31 is formed at thelocal or central section of the long porous sintered structure 30. Withthe configuration of the depressed portion 31, the space of the vaporchannel can be increased, and the long porous sintered structure 30 canbe locally released to meet the bending state of the long poroussintered structure 30 when the flat heat pipe is bent. Furthermore, saiddepressed portion 31 is configured into either of an inclined, bended orstepped surface.

Of which, the inner wall of the flat pipe 10 is of a smooth surface(shown in FIG. 4). Alternatively, referring to FIG. 12, the inner wallof the flat pipe 10 is provided with a grooved capillary structure 18. Asatisfactory condensate diversion effect can be realized via theconfiguration of said grooved capillary structure 18.

Based on above-specified structural configuration for the flat heat pipeof the present invention with a composite capillary structure, themolding process of the preferred embodiment is described in thefollowing steps (referring to FIG. 13):

-   -   (a) Prepare a round pipe 10B, one end pre-closed and the other        end in open state;    -   (b) Prepare at least an elongated mesh grid 20;    -   (c) Prepare at least a metal powder grain 30B of long porous        sintered structure, and cover it onto the elongated mesh grid 20        in a sintering mould 40;    -   (d) Fix the long porous sintered structure 30 onto the surface        of the elongated mesh grid 20 by means of sintering, so to as        prefabricate a composite capillary structure B;    -   (e) Place the prefabricated composite capillary structure B into        the round pipe 10B;    -   (f) Press the round pipe 10B already placed into the composite        capillary structure B, and convert the round pipe 10B into a        flat pipe 10D, meanwhile enabling the composite capillary        structure B to be located in the flat pipe 10D adjacent to the        internal plane of the flat pipe 10D;    -   (g) Enable mating of the composite capillary structure B and        flat pipe 10D by means of sintering;    -   (h) Fill working fluid into the flat pipe 10D and then evacuate        it for sealing.

Alternatively, another molding process of the preferred embodiment isdescribed in the following steps (referring to FIG. 14):

-   -   (a) Prepare a metal round pipe 10B, one end pre-closed and the        other end in open state;    -   (b) Prepare at least an elongated mesh grid 20;    -   (c) Prepare at least a metal powder grain 30B of long porous        sintered structure, and cover it onto the elongated mesh grid 20        in a sintering mould 40;    -   (d) Fix the long porous sintered structure 30 onto the surface        of the elongated mesh grid 20 by means of sintering, so to as        prefabricate a composite capillary structure B;    -   (e) Bend the elongated mesh grid 20 of the composite capillary        structure B so as to form a bending portion on the elongated        mesh grid 20;    -   (f) Pre-press the round pipe 10B for the first time to convert        the round pipe 10B into an embryo flat pipe 10C, but the degree        of pressing only reaches 60%-90% of the preset degree;    -   (g) Place the composite capillary structure B into the round        pipe 10C obtained in aforementioned step (d);    -   (h) Press again the embryo flat pipe 10C already placed into the        composite capillary structure B, and convert it into a shaped        flat pipe 10D, meanwhile enabling the long porous sintered        structure 30 of the composite capillary structure B to be        located onto the lateral wall of the flat pipe 10D adjacent to        the internal plane of the flat pipe 10D, and also enabling the        bending portion 24 of the elongated mesh grid 20 to be extended        into a straight or nearly straight shape;    -   (i) Enable mating of the composite capillary structure B and        flat pipe 10D (by means of sintering);    -   (j) Fill working fluid into the flat pipe 10D and then evacuate        it for sealing, thereby fabricating a finished flat heat pipe of        present invention with composite capillary structure.

In the above methods, the long porous sintered structure 30 of thecomposite capillary structure B is preferably fixed at two sides on thesurface of the elongated mesh grid 20.

Moreover, for the embryo flat pipe 10C pre-pressed by the round pipe10B, its flat cross section is pressed by full section. Alternatively,referring to FIG. 15, the flat cross section is pressed by partialsection. The pre-pressed flat cross section is used for preventingoverturn and displacement of composite capillary structure B not yetsintered.

Referring to FIG. 16, corrugated surface expanded portions 32(rectangular, bended, stepped and reversed shapes) are formed onto oneor two sides of the long porous sintered structure 30, so theevaporation effect of the working fluid for the long porous sinteredstructure 30 can be improved to obtain better heat conductionefficiency.

Referring to FIG. 17, said elongated mesh grid can be placed in theinterval space between the top and bottom walls 11, 12 of the chamber 15of the flat pipe 10.

1. A flat heat pipe with composite capillary structure, comprising: aflat pipe, made of metal into a flat and enclosed hollow pipe bodyhaving a top wall, a bottom wall, two lateral walls and a chamber; theflat pipe having an evaporation section and a condensation section, andboth ends of the flat pipe are enclosed; moreover, the chamber is at anevacuation state; alternatively, the chamber of the flat pipe is filledwith working fluid; an elongated mesh grid, made of metal, located inthe chamber of the flat pipe; the elongated mesh grid is extended fromthe evaporation section to the condensation section of the flat pipe; along porous sintered structure, made of metal, located onto eitherposition in the chamber of the flat pipe; the long porous sinteredstructure is extended from the evaporation section to the condensationsection of the flat pipe; the porous sintered structure and theelongated mesh grid are prefabricated securely into a compositecapillary structure, and the composite capillary structure is placedbetween the top and bottom walls of the chamber of the flat pipe.
 2. Thestructure defined in claim 1, wherein a local hollowed portion is formedat the central section of the elongated mesh grid between theevaporation section and condensation section of the flat pipe; moreover,a coupling surface of sintered structure is reserved at the centralsection of the elongated mesh grid for coupling the long porous sinteredstructure.
 3. The structure defined in claim 1, wherein a single or aplurality of spacing notches is arranged at local section of theelongated mesh grid, in response to the bending state of the elongatedmesh grid.
 4. The structure defined in claim 1, wherein at least adepressed portion is formed at the local or central section of the longporous sintered structure; said depressed portion is configured intoeither of an inclined, bended or stepped surface.
 5. The structuredefined in claim 1, wherein the long porous sintered structure islocated adjacent to two lateral walls, or one lateral wall, or at aspacing with the lateral wall in the chamber of the flat pipe.
 6. Thestructure defined in claim 1, wherein the inner wall of the flat pipe isprovided with a smooth surface or a grooved capillary structure.
 7. Thestructure defined in claim 1, wherein said corrugated surface expandedportions are formed onto one or two sides of the long porous sinteredstructure, so as to improve the evaporation effect of the working fluidfor the long porous sintered structure.
 8. The structure defined inclaim 1, wherein the and the elongated mesh grid is placed between thetop and bottom walls of the chamber of the flat pipe, and at one isplaced at the interval space between the top and bottom walls.
 9. Thestructure defined in claim 1, wherein the molding process of the flatheat pipe comprises the following steps: (a) preparing a round pipe, oneend pre-closed and the other end in open state; (b) preparing anelongated mesh grid; (c) preparing a metal powder grain of long poroussintered structure, and covering it onto the elongated mesh grid in asintering mould; (d) fixing the long porous sintered structure onto thesurface of the elongated mesh grid by means of sintering, so to asprefabricate a composite capillary structure; (e) placing theprefabricated composite capillary structure into the round pipe; (f)pressing the round pipe already placed into the composite capillarystructure, and convert the round pipe into a flat pipe, meanwhileenabling the composite capillary structure to be located in the flatpipe adjacent to the internal plane of the flat pipe; (g) fillingworking fluid into the flat pipe and then evacuating said flat pipe forsealing.
 10. The structure defined in claim 9, wherein the elongatedmesh grid of the composite capillary structure is bent to form a bendingportion before the composite capillary structure is placed into theround pipe; then the round pipe is pre-pressed and bent to convert theround pipe into an embryo flat pipe, but the degree of pressing onlyreaches 60-90% of the preset degree; the composite capillary structureis then placed into the embryo flat pipe; then the embryo flat pipe ispressed again to convert itself into a flat pipe, meanwhile enabling thebending portion of the elongated mesh grid to be extended into astraight or nearly straight shape.
 11. The structure defined in claim 9,wherein the round pipe is pre-pressed to convert into an embryo flatpipe, with the flat cross section pressed by full or partial section.12. The structure defined in claim 9, wherein the composite capillarystructure and the flat pipe are mated by means of sintering before theflat pipe is filled with working fluid and evacuated for sealing.